package czk.concrent.juc.semaphore.practice;

import java.sql.*;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.Executor;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicIntegerArray;

/**
 * @Author:ChenZhangKun
 * @Date: 2021/7/22 21:27
 */
public class SemaphoreDataSourcePractice {
    public static void main(String[] args) {
        MyConnectionPool pool=new MyConnectionPool(5);
        for (int i = 0; i < 10; i++) {
            new Thread(()->{
                // 借连接
                Connection connection= null;
                try {
                    connection = pool.borrow();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                // 休眠
                try {
                    TimeUnit.SECONDS.sleep(2);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                // 还连接
                pool.back(connection);
            }).start();
        }
    }
}

class MyConnectionPool {
    // 线程池大小
    private int poolSize;
    // 限制量
    private Semaphore semaphore = new Semaphore(3);
    // 存放连接的数据
    private Connection[] connections;
    // 原子数组
    private AtomicIntegerArray atomicIntegerArray;

    public MyConnectionPool(int poolSize) {
        this.poolSize = poolSize;
        // 线程池大小
        connections = new Connection[poolSize];
        atomicIntegerArray = new AtomicIntegerArray(new int[poolSize]);
        for (int i = 0; i < poolSize; i++) {
            connections[i] = new MyConnection();
        }
    }

    /**
     * 借连接
     *
     * @return
     * @throws InterruptedException
     */
    public Connection borrow() throws InterruptedException {
        // 阻塞
        // 不为0则继续执行
        semaphore.acquire();
        for (int i = 0; i < poolSize; i++) {
            // 拿到值
            int j = atomicIntegerArray.get(i);
            if (j == 0) {
                if (atomicIntegerArray.compareAndSet(i, 0, 1)) {
                    System.out.println("拿到连接了");
                    return connections[i];
                }
            }
        }
        return null;
    }

    /**
     * 归还连接
     *
     * @param connection
     */
    public void back(Connection connection) {

        for (int i = 0; i < poolSize; i++) {
            if (connections[i] == connection) {
                // 是这个连接
                boolean b = atomicIntegerArray.compareAndSet(i, 1, 0);
                if (b) {
                    // 归还成功
                    // 归还连接
                    // 计数器加1
                    semaphore.release();
                }
            }
        }
    }
}

// 连接
class MyConnection implements Connection {

    @Override
    public Statement createStatement() throws SQLException {
        return null;
    }

    @Override
    public PreparedStatement prepareStatement(String sql) throws SQLException {
        return null;
    }

    @Override
    public CallableStatement prepareCall(String sql) throws SQLException {
        return null;
    }

    @Override
    public String nativeSQL(String sql) throws SQLException {
        return null;
    }

    @Override
    public void setAutoCommit(boolean autoCommit) throws SQLException {

    }

    @Override
    public boolean getAutoCommit() throws SQLException {
        return false;
    }

    @Override
    public void commit() throws SQLException {

    }

    @Override
    public void rollback() throws SQLException {

    }

    @Override
    public void close() throws SQLException {

    }

    @Override
    public boolean isClosed() throws SQLException {
        return false;
    }

    @Override
    public DatabaseMetaData getMetaData() throws SQLException {
        return null;
    }

    @Override
    public void setReadOnly(boolean readOnly) throws SQLException {

    }

    @Override
    public boolean isReadOnly() throws SQLException {
        return false;
    }

    @Override
    public void setCatalog(String catalog) throws SQLException {

    }

    @Override
    public String getCatalog() throws SQLException {
        return null;
    }

    @Override
    public void setTransactionIsolation(int level) throws SQLException {

    }

    @Override
    public int getTransactionIsolation() throws SQLException {
        return 0;
    }

    @Override
    public SQLWarning getWarnings() throws SQLException {
        return null;
    }

    @Override
    public void clearWarnings() throws SQLException {

    }

    @Override
    public Statement createStatement(int resultSetType, int resultSetConcurrency) throws SQLException {
        return null;
    }

    @Override
    public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
        return null;
    }

    @Override
    public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
        return null;
    }

    @Override
    public Map<String, Class<?>> getTypeMap() throws SQLException {
        return null;
    }

    @Override
    public void setTypeMap(Map<String, Class<?>> map) throws SQLException {

    }

    @Override
    public void setHoldability(int holdability) throws SQLException {

    }

    @Override
    public int getHoldability() throws SQLException {
        return 0;
    }

    @Override
    public Savepoint setSavepoint() throws SQLException {
        return null;
    }

    @Override
    public Savepoint setSavepoint(String name) throws SQLException {
        return null;
    }

    @Override
    public void rollback(Savepoint savepoint) throws SQLException {

    }

    @Override
    public void releaseSavepoint(Savepoint savepoint) throws SQLException {

    }

    @Override
    public Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
        return null;
    }

    @Override
    public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
        return null;
    }

    @Override
    public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
        return null;
    }

    @Override
    public PreparedStatement prepareStatement(String sql, int autoGeneratedKeys) throws SQLException {
        return null;
    }

    @Override
    public PreparedStatement prepareStatement(String sql, int[] columnIndexes) throws SQLException {
        return null;
    }

    @Override
    public PreparedStatement prepareStatement(String sql, String[] columnNames) throws SQLException {
        return null;
    }

    @Override
    public Clob createClob() throws SQLException {
        return null;
    }

    @Override
    public Blob createBlob() throws SQLException {
        return null;
    }

    @Override
    public NClob createNClob() throws SQLException {
        return null;
    }

    @Override
    public SQLXML createSQLXML() throws SQLException {
        return null;
    }

    @Override
    public boolean isValid(int timeout) throws SQLException {
        return false;
    }

    @Override
    public void setClientInfo(String name, String value) throws SQLClientInfoException {

    }

    @Override
    public void setClientInfo(Properties properties) throws SQLClientInfoException {

    }

    @Override
    public String getClientInfo(String name) throws SQLException {
        return null;
    }

    @Override
    public Properties getClientInfo() throws SQLException {
        return null;
    }

    @Override
    public Array createArrayOf(String typeName, Object[] elements) throws SQLException {
        return null;
    }

    @Override
    public Struct createStruct(String typeName, Object[] attributes) throws SQLException {
        return null;
    }

    @Override
    public void setSchema(String schema) throws SQLException {

    }

    @Override
    public String getSchema() throws SQLException {
        return null;
    }

    @Override
    public void abort(Executor executor) throws SQLException {

    }

    @Override
    public void setNetworkTimeout(Executor executor, int milliseconds) throws SQLException {

    }

    @Override
    public int getNetworkTimeout() throws SQLException {
        return 0;
    }

    @Override
    public <T> T unwrap(Class<T> iface) throws SQLException {
        return null;
    }

    @Override
    public boolean isWrapperFor(Class<?> iface) throws SQLException {
        return false;
    }
}
